One caveat ... please let the bacon grease cool a little before you pour it into a glass container. If it's too hot, the glass could break when you pour it in (never a good thing). Pour in a little, add a LEAD-FREE (please) wick, stabilizing it by tying it around a pencil or spoon which you then rest across the top of the jar. Then pour the rest of the grease. This is essentially what the earliest candles were. There is usually a bit more soot produced than with most 'conventional' candles, but it's a great way to recycle.

Idiots who think this can cause a fire.... does a candle catch fire when you light the wick? No. Because the melted wax at the base of the wick soaks up the wick and burns there rather than in the container. Same applies to bacon grease, kerosene in a lamp, cooking oil candles. Why does such simple technology befuddle you?